1. Field of the Invention
The present invention relates to an improvement of an apparatus for arraying conductive balls by allowing a ball cup housing the conductive balls to relatively move over an arraying jig in which ball insertion parts are formed in a predetermined pattern. More particularly, the invention relates to a conductive ball arraying apparatus designed not to stagnate conductive balls coming in contact with an inner wall surface of a ball cup by floating and vibrating the ball cup relative to an arraying jig. Still more particularly, the invention relates to a conductive ball arraying apparatus designed to easily detect or prevent the biting between a ball cup and an arraying jig by floating the ball cup relative to the arraying jig.
2. Description of the Related Art
In a solder ball mounting apparatus that mounts solder balls on electrodes formed in a predetermined array pattern on a mounting object, the solder balls have been decreased in size and mounting objects such as wafers have been increased in size, thereby enhancing the number of solder balls to be mounted at a time. In this situation, in order to reduce defects in arraying or mounting the solder balls, JP-A-2006-303341 discloses an apparatus for providing an arraying jig such as an array mask on a wafer as a mounting object on which a flux is printed and directly dropping the solder balls onto the electrodes on the wafer while allowing the ball cup to move over the arraying jig.
However, in such a kind of conductive ball array apparatus, since the solder balls close to the lower end of the inner wall surface contacting the rear side of the ball cup in the moving direction do not move and stay and is affected by the gravity, the solder balls may settle down into through holes of the array mask to be broken or deformed, thereby causing a defective product. The broken pieces of the solder balls may cause a defect of another product.
In order to reduce the defects in arraying or mounting the solder balls, Japanese Patent No. 3271482 discloses an apparatus that directly drops the solder balls on electrodes of an electronic substrate by providing an arraying jig (template in Japanese Patent No. 3271482) such as an array mask on the electronic substrate as a mounting object on which a flux is printed and allowing a ball cup (solder ball housing part in Japanese Patent No. 3271482) to move over the arraying jig.
However, in such a kind of conductive ball arraying apparatus, when a tension of the arraying jig is not proper, when the plane precision is failed, or when the height of the ball cup relative to the arraying jig is not properly set, the conductive balls in the ball cup may be bitten between the ball cup and the arraying jig during the ball arraying operation.
When the biting occurs and the moving speed of the ball cup is too high, the solder balls may be broken. It could be considered to reduce the moving speed of the ball cup. However, if the moving speed of the ball cup is reduced, productivity may be decreased. Accordingly, the moving speed of the ball cup should be set properly. However, in an apparatus in which the ball cup moves fixed to moving means at a predetermined height, it is difficult to detect the biting of the solder balls of which a biting load is very small.